U.S. lawmakers and international health officials warned against siphoning funds for Ebola to fight the Zika virus one day after the Obama administration announced plans to do just that.

“While new cases of Ebola have been dramatically reduced, Ebola is not over. And the conditions that made it an epidemic persist,” said Democratic Senator Ed Markey at a hearing of the Foreign Relations Subcommittee on Africa.

More than 11,000 people died of Ebola in West Africa in 2014 and 2015, prompting a global health scare as the virus reached the United States and Europe. Congress appropriated $5.4 billion in emergency funding to combat Ebola, some of which has yet to be spent.

On Wednesday, the White House announced it will redirect nearly $600 million in funds, much of it from Ebola resources, to fight the spread of the Zika virus. Over the last year, Zika has spread rapidly in much of the Americas and is blamed for devastating birth defects.

The move is short-sighted, according to health officials who testified on Capitol Hill.

“If it’s about shifting from one priority to another, then it’s worrying, because one of the lessons we learned from Ebola [is] that we need to be prepared,” said Sophie Delaunay of the French group Doctors Without Borders. “It’s going to come back.”

Lawmakers of both parties agreed that Ebola must not be ignored.

“The [Ebola] epidemic decimated already-weak health care systems in three affected [West African] countries,” said Republican Senator Jeff Flake. “It also has continued to wreak havoc on their economies, complicating recovery for governing institutions and hampering a return to normalcy.”

“All the conditions that led Ebola to go from largely unknown to a significant challenge to a global concern are still there,” said Democratic Senator Chris Coons. “There is an animal reservoir of Ebola that has probably been active in West Africa for 40 years, we have now discovered. There have probably been a whole series of small outbreaks in remote villages that the rest of the world never knew about.”

“And there is, of course, the possibility that this virus will mutate and become more lethal,” Coons added.

The Obama administration says it is forced to shift funds from from Ebola to Zika because Congress has not approved a $1.9 billion request to respond to the mosquito-borne Zika virus.

Health officials urged lawmakers to embrace a comprehensive approach to fighting epidemics rather than piecemeal funding as emergencies arise.

“We need to structure our financing of response to infectious disease – whether they are outbreaks or whether they’re protracted issues – in a way that avoids repeat disease earmarks and repeat emergency funding,” said Amanda Glassman of the Center for Global Development.

“The big blind spot is: we are not reaching the last mile,” said Raj Panjabi, a Liberian-born physician and co-founder of the aid group Last Mile Health.

“There are 400 million to a billion people on the planet who live out of reach of health care, even in the 21st Century. And if we don’t recon with that, we’re not going to be able to stop these outbreaks from happening,” Panjabi said.